Deasphalting mixtures of hydrocarbons



Patented Mar. 4, 1952.

DE'A'SPH'AETIV'NG MIXTURES F HYnRooARBoNs Harold C Myers}. Woodbury; N.J., assign'or to- Socony-Vacuum Oil Company; Incorporated, a:

oorporationof New York No -Drawing. Application A'ugust 27,1947,

- Serial No. 770952 10I Claims. (G1. 196-14.46)

The present. invention relates-. tothe; treatmerit. of. mixtures ofhydrocarbons. with liquidnormally. gaseous. hydrocarbons and'-, morelpar.- ticularly, to the treatmentof mixturesof hydro.- oarbonscontainingasphalt with liquid normal 13' gaseous hydrocarbons. and? organic.carbonates to separate an asphaltic component; I

In the' years subsequent to 1934- a, number of patients haveissuedrelating, generally, to the deasph'ailtingr of mixturesi ofhydrocarbons and; specifically, to" the deasphalting of" mineral oil.For eit a mplefi. U1 Si Patent'No. 948,296 contains" a: desj. ipti'on ofamethod of treating crude oils. it e.- d'sphalt contaihi-ngoil's-whichhave not been subj ed t'o excessive temperatures;withsolvent's' have the function of dissolving the oil.- 7 div-notdissolve-the bitumens. Suchv sn'lvehtssare stated. inthis patent t'ovbe: light petrol m"; hydrocarbons, such: as naphtha; casinghead gasolinelight: petroleum: fractions composed f: propane; butane". and;isobutane; certain alcohols... ether and mixtures thereof, acetone,-etc; ater in1.U-.. S; Patent No.- $002,004 thehydrocarbons:- of. theforegoing. list of asphaltprecipitants. were: termed. normally gaseous:liquefiedhydrocarbons. 'I hus i thereis abroad. desi 'tion. 011deasphalting. agents which inciud within itsscope: the normally gaseous.Belief-i d hydrocarbonsast a specific typeof de asph ing agent.

" r t rm asphalt, as used in generically g the material insoluble: inthecon deasphalting agents, has likewise; been veral definitions which inessence-have meaning. Thus, in Ul S. Patent; No. asphalt and bitumens.wouldappear to ymous terms; the other hand; Asphalts and AlliedSubstances:" 165th vol. I, page 61, defines asphalt as,.

in Chemical Refining of Petroleum?" Kali'chev pplied to a species: ofbitumen," while" sky-Stagner, asphalt is defined in theGlossary of Termsas Solid or semi-solidbitumen found in nature (natural asphalt) ormanufactured by the oxidation, distillation on other treatment. ofmineral oils (artificial asphalt)." While these definitions diilerinsome respects those skilled.

in the artlofpet'roleumx ren'nmgjwhen discussing the deasphaltingi oi;crude's or; lubricating. fractions: or: other mixtures; of?hydrocarbons: by

treatment? with. deasphai'tingf agent's cbl'i'sifif'the?suiistanceinsoliibieinthe deasphaftlnsfasents lie asphalt The terms"asphalt'f and deasnhaltinn agents used hereinafter: in: thenirwngseflcrthiihthelestsentence The: present; invention does: notinclude new or. novel manipulations of: the mixture of i hydrocarbons tobe: deasphalted butv provides for the: use of a novel solvent mixture:in operations: disclosed. by the: prior art. Inother words; the novelsolvent mixture is used. as a solvent inthe? prior art processes ofdeasphalting.

The novelsolventmixture. comprises amixture of one or more of. the wellknown or con ventional'. deasphalting. agents and a modifier; Theparticular mechanism by which the. modi' fien produces the novelresults. not entirely understood. v That is tosay,. it is not clearwhether the modifier reduces. the solubility of; the: asphalt in the:deasphaltingagent thereby reducing the Conradson number of the:rafiinatev orv decreases the solubility of the rafiinate. in the liquidasphalt thereby increasing the yield 01' whether the unexpected overallimprovement is the: result of. some other phenomenon. or' phenomena.However, it has been establishing. as. shown hereinafter that improvedresults compared to those. of the: prior artcan be achieved. in eitherof two waysby the use: of a deas'phalting mixture comprising a, modifierin conjunction with a conventional deasphalting agent. That is to say, adeasphalted oil of. higher quality than that produced when treating thesame charge stock with a conventional. deasphalting agent can beobtained by using one of the novel modifiers in conjunction with thesame deasphaltingagent and at nosacrifice'in yield. Onthe other hand,vbyusing a novel modifierin conjunction with a known deasphalting agent,the deasphalting. operation can. be carriedout in such a manner as toproduce a higher yield of deasphalted oil than can be obtained with thesame charge stock using the some deasphalting agent alone and at. nosacrifice in, quality;

The novel modifiers are a special class -of the group, organic esters;towit: the carbonate of aliphatic, cycloaliphatic, and aromatichydrocarbon and heterocyclic. compounds. The most readily available and;for. practical reasons, the prefered esters are methyl and ethylcarbonate. (CH3O)2CO- and (C2H5O)2CO respectively. Typicaliof the othermodifiers are the carbonate of cyclohexane,. (CtH'nOYzCO, and thecarbonates of fura'n, pyrrole and thiophene conforming. to the generalformula; (ROMCO where R? is the monovalent residue of an: aliphatic; or:cyclealiphatic, or aromatic hydrocarbons oraheterm cyclic" compoundprovide an improved deasphalting agent for use in deasphalting mixturesof hydrocarbons and particularly for use in deasphalting residualmineral oils. The present invention has as an- 4 second, the raflinateis much heavier, i. e. the rafiinate had a viscosity of 135.1 seconds at210 degrees Fahrenheit as compared with 99.9 seconds for the rafiinatewhen propane without a other object to provide a deasphalting agent 5modifier was the deasphalting agent. On the which, in known processes,will produce the same other hand, when propane without a modifierquantityof lighter colored deasphalted oil having was used as thedeasphalting agent (tests 1 and a lower carbon residue than deasphaltedoil 2) and the tower temperatures controlled to proprepared byconventional deasphalting. The duce substantially the same yield ofrafiinate the present invention has as a further object to procolor ofthe rafiinate was much darker, 115 as vide a deasphalting agent which,in known procompared with 62, and the viscosity significantly cesses,will produce a larger quantity of higher lower. viscosity, lightercolored deasphalted oil of com- By comparing tests 1, 4 and 6, theefiect of an parable carbon residue to that prepared by conincrease inthe concentration of modifier in the vo l do p a gn aqdi o al 16011deasphalting mixture can be recognized. An int p n ve n s t n v de a dpha s crease in modifier concentration from 1.5 to 2.5 agent wh ch willretain high viscosity 011 conper cent results in an 11 per cent increasein yield. stituents in the raflinate phase whlch are 0 While theviscosity increases slightly, on the other many dlsqarded Wlth theasphalt m conventlonal hand, the carbon residue is the same (i. e.within deasphalting. 'the limit of error). In contrast, when an at- Ingeneral, deasphaltmg Procedur? 15 that tempt is made to obtain-a processyield equal to used inv-conventional deasphaltmgof 0115. For thagobtamedwith 2.5 per cent modifier in a p s apphed to resldual 0115, th 011 1Sdeasphalting mixture by controlling tower temheated to a temperature atwh1ch the 011 is freely peratures, the yield can be equalled but at afiuld, f 011 15 contacted a closed sacrifice of quality which cannot betolerated. tem w1th the mlxture of deasphaltmg agentf anfi Tests and 5establish the foregoing VWIIBQ FF- i f then z g wlth fg using adeasphalting mixture containing 2.5 per guantmes' i :7 5 g g 3 1 cent ofa modifier, a process yield of 64.3,per cent 0 remove en o y ma an 8 Qwas obtained. When'using propane without any phalt and solution ofrafilnate 1n the mixture or i modifier, a substantially equal processyield of deasphaltmg agent andtmodlfier i??? and 63.6 per cent wasobtained However the rafflremoved .from. the sys em. Two su1 a esequences of operations are illustrated in the g gg zg g fg 3 2 1 233? gggi g wg' u a Process Handbook of Petroleum Refiner (April, g a or of430 as compared w1th 115 and. a carbon residue 1947) at pages 226 to229. The mixture of deof 20 6 cent a c d t 1 0 t T t asphalting agentand modifier is used in the i 7 h S omrare per cen es ratio 1 to 15parts by volume of mixture to 1 c0 t e foregomg' At'exacfly the a partby Volume of on. Preferably, the modifier process ylelcl the color ofthe rafiinate, obtained is used in amounts up to about 20 volume perusing propane as the soledeasphaltmg agent-1s cent of the mixture.Greater amounts of modi- 40 as compared to 115 and carbon 9?- fier canbe used but at the cost or diminishing 25% comparedto w 115mg de paltreturns. Preferably, ethyl carbonate (C2H50)2CO mg agent contammgizfiper cent of fi i is used in the range of 1 to 12 volume per cent (tests4 and 7 Test No. -8 establishes these of the mixture. It is alsopreferred to use de- {nodlfiers f P 11590918 solve SP asphaltingmixture-oil ratios of about 3:1 to 10:1 mg agent In gravlty Settlmg l pthere by vo1ume fore, it is manifest, in view of the data presented Inorder to provide a comparison of the efiect in th foregoing tabulation,that a modifier-for of the novel deasphalting mixture and a prior theclass described hereinbefore cooperates with art deasphalting agent, thefollowing data are well known, conventional deasphalting agents'to t l t5 form a deasphalting mixture which produces ref Table I TestNo 1 2 a- 56 7 "'s- Hydrocarbon mixture; Temperature: 1 7

Top or tower, "F 180 165 180 180 125 180 125 125-180 Bottom of tower, F120 120 120 120 120 120 120 120 Volume ratio:

Deasphalting mixture to oil. 10.1521 10:1 10:1 10.25zl 10:1 8.5:1 8:18:1 Vol. per cent deasphalting agt 98.5 100 100 97.5 100 94.1 100 Vol.per cent modifier... 1. 5 2. 5 5.9 100 Rafiinate yield, vol. per cent57. 8 55. 6 47. 5 64. 3 63. 6 70,9 64.9 s. U. v. at210" F.,seconds 135.1125. 2 99.9 142.4 162.1 192.2 170 Color (Lovibond )4 cell). 62 115 45115 430 350 625 Per cent carbon residue V 0.8 0.8 0.3 1,0 2,0 2, 2 m

i A residual oil having an S. U. V. at 210 F. of 1,058 seconds.

I No separation of ratllnate and asphalt even at low throughout. Thecarbonaceous material remained suspended in the oil-deasphaltingmixture.Y

sults unattainable by. the use of conven'tio deasphalting agents. Thatis to say, th euse' of the novel deasphaltingv mixtures, comprising aconventional deasphalting agent and amodifier selectedfrom thegroupconsisting of car of, aliphatic,cycloaliphatic, and aromatiq carbons andheterocyclic compounds subs-tan 1y completely. miscible in allproportions conventional deasphalting agents makes it possi ble toproduce the same process yield of rafiinate of better color, higherviscosity and lower carbon residue or a better process yield ofraflinate of equivalent quality than can be obtained employi-n thetabulation. In all instances fine, granular,

tarry materials in the amount of 9-14 weight per cent could be separatedby filtration but the mixture of oil and diethyl carbonate did notstratify into a raflinate layer and a liquid asphaltic layer ingconventional deasphalting agents as the sole in gravity separatingoperations. component of a deasphalting mixture. Typical of thetreatment of other residua are A series of tests have furtherestablished that the data submitted hereinafter in Table II obthe use ofa modifier vsuch as diethyl carbonate tained by treating a mixed basecrude, in Table as the so'le component of a deasphaltin'g mixture 10 IIIobtained by treating a West Texas sweet in amounts of 500 to 800Volumeper' cent of remixed base crude, and in Table IV obtained bysidual oil, 1. e. .(CzHsO-J'zCO: oil ratio of 5:1 to furfural refiningafter deasphalting of a mixed 8:1 does not materially afiect the resultsreported base crude:

Table II Processing Conditions-Deasb'hzilting: i

Propane, Per Cent Volume'on Oil Charge 00 800 I800 800 1,000 1,000 800800. 600 600 methyl-Carbonate, Per Cent Volume on Oil Charge 60 35Temperature, F Tower Top. Temperature, F Tower Botto Run Number. e

42. S 2, 205 2,910 3, 160 3, 920 '4, 830 5, 190 5, 250 5, 400 5, 660 7,210 S. U. V. 210 'F. Seconds 1,058 121. 5 140. 5 148. 0 164. 8 186.8193. 6 197.2 197. 9 207. 0 225.9 Viscosity Index 1 v 76 r 74 73 73 73.74 73 75 68 Viscosity Gravity'oonstailt 210 0.007 0. 833 0.8 37 0. 837O. 843 0. 846 0. 849 0.845 0. 848 0. 844 0. 850 Color, Levibond, 54"Cell 750 85 245 165 550 v 415 750 335 750 715 T Carbon Residue, PerCentWeight 0. 7 0.8 1.3 l. l 2. 2 .2. 2 2. 7 r 2. 5 3. 3 3. 4

Specific Gravity @60F. ('Pyc. 77FZ) 1.0361 1.0650 1.0552 1.0718 1.06911.0854 1.0690 1.0794 1.0711 1.0865 Penetration 77F. 24 0 0 4 0 0 4 0 Rand B Melting Point, '"F. 141 203 167. 5 215 178 246 226 180 259 1 Rawresiduum. I Dewaxed 'deasphalted oil.

Table III Processing Conditions-Dessphalting; Propane, Percent'Volume.on Oil Cherge 600 1,000 800 1,000 600 l, 000 l, 000 800 DiethylCarbonate Percent volume on Oil Charge '25 50 75 r 50 Temperature, F,ower Top 180 180 0 180 200 125 200 Temperature, "F, Tower Bottom Yield,Per cent Vol V Deasphaiting. "Overall:

fBrocessing Step.-." Inspections:

Gravity, .A P. 1,- ma-- Specifie Gravity 60F. (Pyc @77F.) Penetration77F Ring and Ball Melting Point, "F

Raw residuum. Dewaxed deasphalted oil.

Table IV Processing Conditions-Deasphalting:

Propane, Per Cent Volume Diethyl Carbonate, Per Cent Volume.vTemperature, "F2, Tower Top Temperature, F., Tower Bottom Run NumberFurfural Extracti n:

Solvent, Per Cent Volume Temperature, F

Run Number Yields, Per Cent Vol. On Process: Deasphalting ExtractionDewaxing, Ultimate Overall:

On Process 0n Crude Proc ssing Step Gravity, A. P. I

Pour Point Fire Point, F. (CO K. V. 100 F. Centistokes K. V. 210 F.Centistokes.. S. U. V. 100 F. Seconds... 8. U. V. 611 210 F. SecondswViscosity Index Viscosity Gravity Constant Viscosity Gravity 210 FColor, Lovibond, 14 CelL Carbon Residue, P r Cent Weight..." Sulfur, PerCent Weight Asphalt:

Specific Gravit (10 60 F Penetration 6:) 77 F Rina and Ball MeltingPoint, F

Furfural Extract:

Specific Gravity 60 F Processing Conditions-Deasphalting:

Propane, Per Cent Volume Diethyl Carbonate, Per Cent Vo1urneTemperature, F., Tower Top Temperature, F., Tower Bottom.. Run NumberFuriural Extraction:

Solvent, Per Cent Volume Temperature, "F

b Yields; Per Cent Vol. On Process:

Dnasphaltinq Extraction Dewaxing, Ultimate Overall:

On Process OnCrude... Processing Step Gravity, A. P. I Gravity, Specific60 F. Pour Point, Flash Point, F. (000). Fire Point, F. (COO) K. V. 100F. Centistokes. K.'V. 210 F. Cent stokes V. 100 F. Seconds V. 210 F.Seconds" Viscosity Index Viscosity Gravity Constant Viscosity Gravity210 F--. Color, Lovibond, 14 Cell .i Carbon Residue, Per Cent WeightSulfur, Per Cent Weight Asphalt:

Specific Gravity 60 F Penetration 77 F Ring and Ball Melting Point, "FFurfural Extract:

Specific Gravity 60 F .s

I Raw residuum.

i Waxy deasphalted oil.

3 Waxy Furfural Raifinate. 4 Dewaxed raiiinate.

I Finished oil.

Typical of the results produced by the use of the novel deasphaltingmixture (deasphalting agent plus carbonates of aliphatic orcyclialiphatic, or aromatic, or heterocyolic hydrocarbons or mixtures orthe:- foregoing) in the: deasphalting of a mixed base crude high. in.asphaltic materials, are; the data presented in Table V':

Table V Charge stock-Residuum from mixed base crude high in asphalticmaterials Per cent volume of crude-16.4

Specific gravity 77/60 BE-019960 SLTIV. 210 F.-, seconds9l7'Carbonresidue, weight per cent-16.1

[DEASPHALTIN G1,

A B O Deasphalting Agent. percent vol 600 800 800 Modifier, percent vol50 75 Temperature, F. to 125- 180 180 Temperature, F, bottom I20 I20 120Deasphalted Oil:

Yield, percent vol 55.1 60. 66. 8 S. U. V. 210 F. seconds 156.0 165. 3205 Color Lovibond 300 13 300' Conradson Carbon residue percent. wt. 2.22; 0 Ii 0; Asphalt:

Specific gravity. 1. 0739 l. 0864 110968 FURFURAL REFIN'IN'G' Percentvol. iuriural. f 200 200 200 Temperature, F 250 250 250 Waxy Railinate:

Yield.percent vol s..- f 71.4 68.0. 61. 3 S. U. V. 210 F. seconds 1'32.6 136. 5 155. 3 Conradson Carbon residue percent wt. 0. B 0. 7 1. 0Dewaxed Ratfinate:

Yield, percent vol 85. 4 86. 4 84. 3 S. U. V. 100 F. seconds. 2, 530 2,670 3, 500 S. U. V. 210 F. seconds 151. 2 156.1 2. 5 Viscosity index 9595 94 Conradson Carbon residue percent wt. 1. 0 0. 7 1. 1 Overall yieldon charge percent vol. 33. 5 35. 6 34. 6 Overall yield on crude percentvol. 5. 50 5. 85 5. 68 Barrels of S. A. E. 30 (65 seconds 210 F. per10,000 barrels of crude) Barrels bright stock 550 585 568 Barrels 150100 F. (neutral) (43 210 F.) 572 033 694 Total Barrels S. A. E. 30 1,122l, 218 l, 262

In other words, due to the high viscosity of the raifinate produced bydeasphalting with the novel deasphalting mixture, between about 96 andabout 140 barrels more of S. A. E. 30 motor oil can be produced from10,000 barrels of this crude than can be obtained when deasphalting withconventional deasphalting agents. This represents an increased yield ofS. A. E. 30 motor oil from this crude of from about 8.5 to about 12.5per cent. When it is recalled that, at this time of short supply, lowviscosity neutral oils are available in quantities far greater than thedemand, the importance of the opportunity presented by the noveldeasphalting mixture to balance the supplies of neutral oil and heavylubricating fractions is recognized. In other words. the noveldeasphalting mixture, due to the high viscosity of the finished oil,makes it possible for the refiner to use a greater portion (11 to 21 percent more) of the low viscosity neutral oils of which there is a largeexcess in blending the lubricating oil fraction to an oil ofpredetermined viscosity such as S. A. E. 30.

As used hereinbefore and hereinafter in the claims, the termdeasphalting agent includes within its scope those hydrocarbons,mixtures of hydrocarbons, organic compounds and the like which are knownto those skilled in the art to function as diluents, or solvents for thenonasphaltic components of petroleum and the term deasphalting mixtureincludes within its scope deasphalted oil of given quality as measuredby arequired Conradson carbon, residue of about 0.4

5 to about 6 weight per cent than can be obtained by conventionalsolvent deasphalting which comeprises contacting a fluid charge stockcontaining asphaltic material with a mixed deasphalting agent consistingessentially of. about 1, to about. 20 volume per cent of an organiccarbonate and the. balancemajor deasphaltingv agent, deasphalting saidcharge stock at a deasphalting temperature above that temperature atWhich parafiin. wax is substantially insoluble in said mixture ofcharge, stock and mixed deasphalt. ing agent. to about 206 F- and thenearer the required Conradson carbon residue is to 0.4 weight per centthe higher the deasphalting temperature in the presencev of a givenconcentration. of said organic carbonate, and separating adeasphaltedoil having said required Conradson. carbon residue. in greater yieldthan can be obtained when deasphalting said charge stock to saidrequired Conradson carbon residue. using, said. major deasphalting,agent as the sole deasphalting agent.

2. The method as: set. forth and described in claim 1. wherein theorganic carbonate. is diethyl carbonate.

The method as. set. forth and described in claim 1 wherein the majordeasphalting agent is liquid normally gaseous hydrocarbon.

4. The invention as set forth and described in claim 1 wherein the majordeasphalting agent is propane.

5. A method of producing a greater yield of deasphalted oil of givenquality as measured by a Conradson carbon residue of about 0.3 to about4 weight per cent than can be obtained by deasphalting a given chargestock with propane as the sole deasphalting agent at deasphaltingtemperatures of 125 F. to 160 F. which comprises contacting a fluidcharge stock containing asphaltic material with a mixed deasphaltingagent consisting essentially of about 1 to about 6 volume per cent ofdiethyl carbonate and the balance propane, deasphalting said chargestock at a deasphalting temperature of about 165 to about 206 F. and thenearer the required Conradson carbon residue of the deasphalted oil isto 0.3 weight per cent the higher the deasphalting temperature and thelower the concentrathe mixture of one or more of said deasphalting tionof diethyl carbonate, and separating a deasphalted oil having saidrequired Conradson carbon residue in greater yield than can be obtainedwhen deasphalting said charge stock to said required Conradson carbonresidue using said propane as the sole deasphalting agent.

6. A method of producing a greater yield of deasphalted oil of givenquality as measured by a required Conradson carbon residue of about 0.4to about 6 weight per cent than can be obtained by conventional solventdeasphalting which comprises contacting a fluid charge stock containingasphaltic material with a mixed deasphalting agent consistingessentially of about 1 to about 20 volume per cent of an organiccarbonate and the balance major deasphalting agent in the ratio of about1 to about 15 parts by volume of said mixed deasphalting agent to about1: part by volume of charge stock, deasphalting said charge stock at adeasphalting temperature above that temperature at which paraflin wax issubstantially insoluble in said mixture of charge stock and mixeddeasphalting 11. agent to about 206 F. and the nearer the requiredConradson carbon residue is to 0.4 weight per cent the higher thedeasphalting temperature in the presence of a given concentration ofsaid organic carbonate, and separating a deasphalted oil having saidrequired Conradson carbon residue in greater yield than can be obtainedwhen deasphalting said charge stock to said required Conradson carbonresidue using said major deasphalting agent as the sole deasphaltingagent.

7. The method as set forth and described in claim 6 wherein the organiccarbonate is diethyl carbonate.

8. The method as set forth and described inclaim 6 wherein the majordeasphalting agent is liquid normally gaseous hydrocarbon.

9. The invention as set forth and described in claim 6 wherein the majordeasphalting agent is propane.

10. A method of producing a greater yield of deasphalted oil of givenquality as measured by a Conradson carbon residue of about 0.3 to about4 weight per cent than'can be obtained by deasphalting a given chargestock with propane as the sole deasphalting agent at deasphaltingtemperatures of 125 F. to 160 F. which comprises contacting a fluidcharge stock containing asphaltic material with a mixed deasphaltingagent consisting essentially of about 1 to about 6 volume per cent ofdiethyl carbonate and the balance propane in the ratio of about 1 toabout 15 parts by volume of said mixed deasphalting agent to about 1part by volume of said charge stock, deasphalting said charge stock at adeasphalting temperature of about 165 to about 206 F. and and nearer therequired Conradson carbon residue of the deasphalted oil is to 0.3weight per cent the higher the deasphalting temperature and the lowerthe concentration of diethyl carbonate, and separating a deasphalted oilnaving said required Conradson carbon residue in-greater yield than canbe obtained when deasphalting said charge stock to said requiredConradson carbon residue using said propane as the sole deasphaltingagent.

I HAROLD C. MYERS.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Great Britain July 11, 1934

1. A METHOD OF PRODUCING A GREATER YIELD OF DEASPHALTED OIL OF GIVENQUALITY AS MEASURED BY A REQUIRED CONRADSON CARBON RESIDUE OF ABOUT 0.4TO ABOUT 6 WEIGHT PER CENT THAN CAN BE OBTAINED BY CONVENTIONAL SOLVENTDEASPHALTING WHICH COMPRISES CONTACTING A FLUID CHARGE STOCK CONTAININGASPHALTIC MATERIAL WITH A MIXED DEASPHALTING AGENT CONSISTINGESSENTIALLY OF ABOUT 1 TO ABOUT 20 VOLUME PER CENT OF AN ORGANICCARBONATE AND THE BALANCE MAJOR DEASPHALTING AGENT, DEASPHALTING SAIDCHARGE STOCK AT A DEASPHALTING TEMPERATURE ABOVE THAT TEMPERATURE ATWHICH PARAFFIN WAX IS SUBSTANTIALLY INSOLUBLE IN SAID MIXTURE OF CHARGESTOCK AND MIXED DEASPHALTING AGENT TO ABOUT 206* F. AND THE NEARER THEREQUIRED CONRADSON CARBON RESIDUE IS TO 0.4 WEIGHT PER CENT THE HIGHERTHE DEASPHALTING TEMPERATURE IN THE PRESENCE OF A GIVEN CONCENTRATION OFSAID ORGANIC CARBONATE, AND SEPARATING A DEASPHALTED OIL HAVING SAIDREQUIRED CONRADSON CARBON RESIDUE IN GREATER YIELD THAN CAN BE OBTAINEDWHEN DEASPHALTING SAID CHARGE STOCK TO SAID REQUIRED CONRADSON CARBONRESIDUE USING SAID MAJOR DEASPHALTING AGENT AS THE SOLE DEASPHALTINGAGENT.